Biologists confirm first invasive Manila clam colonies along northeastern US coastline

A collaborative team of biologists has confirmed the establishment of the invasive Manila clam, Ruditapes philippinarum, along the northeastern U.S. coastline, marking a significant ecological development. This discovery was made on July 7, 2026, by researchers from the University of Massachusetts Amherst, MIT Sea Grant, and the Center for Coastal Studies.

Invasive Manila Clams Found in Boston Harbor

The invasive Manila clam, previously absent from the northwestern Atlantic, has now been identified in large numbers along the intertidal zones of Boston Harbor’s Spectacle Island. The team’s findings, published in Biological Invasions, highlight a rare event where an invasive species establishes itself in a new environment.

This species has previously spread across coastlines in the Northern Hemisphere, including the American Pacific Coast and Europe, due to both accidental and intentional introductions. The Manila clam, valued at a $7 billion annual market, poses potential risks to native shellfish populations.

Research Collaboration and Discovery Process

Marine scientist Aly Putnam, the lead author of the study, noted, "Given that Manila clams are everywhere else in the Northern Hemisphere, it was only a matter of time before they showed up here, and we've been keeping an eye out for them." The investigation began after a text from El Fernekees Hartshorn, a co-author and recent undergraduate, suggested that a clam found on Spectacle Island might be a Manila clam.

Following this tip, Putnam and co-investigator Carolina Bastidas began searching for Manila clam shells, which they found in abundance. Their work was supported by James T. Carlton, a noted expert on marine invasive species, who encouraged them to look for live specimens.

Potential Impact on Local Ecosystems

While the Manila clam is a popular seafood choice, its introduction raises concerns about its impact on local ecosystems. It can outcompete native species and affect local biodiversity. However, the clam also serves as a food source for various animals, including seabirds and crabs.

“We do need more research to understand the Manila clam's potential effects on the shellfishing industry and ecological communities,” said Bastidas. As the research continues, the implications of this invasive species on the northeastern U.S. waters remain uncertain.